a) Field of the invention
The present invention relates to a variable focal length lens system, and more specifically a compact variable focal length lens system which uses a solid-state image pickup device or the similar means as an image sensor, and is suited for use with electronic still cameras and video cameras.
b) Description of the prior art
In the recent years, it is demanded to reduce manufacturing costs and dimensions of variable focal length lens systems which are to be used with video cameras and so on. Under the current circumstances, in particular, it is demanded to configure these compact variable focal length lens systems so as to have high variable focal length ratios and wide field angles.
As variable focal length lens systems configured so as to meet these demands, there are known the lens systems disclosed by Japanese Patent Kokai Publication No. Hei 2-291,515 and No. Hei 1-246,517, each of which is composed of three or a smaller number of lens units including two movable lens units, and has a simple lens moving mechanism and a variable focal length ratio of 3 or higher.
However, each of the above-mentioned conventional examples adopts a front lens component which cannot be said to be sufficiently small, cannot have a variable focal length ratio on the order of 3 without using a non-homogenous lens component and cannot be configured so as to have a sufficiently wide field angle in any case, or has a field of 53.degree. at widest at a wide position thereof.